Methods of creating a color conversion table are known. The color conversion table is used to achieve color matching in a device such as a color printer, by converting one color data about an uniform color space that does not depends on the device characteristics, to another color data about another color space that depends on the device characteristics.
Japanese Patent Application Publication No. 2002-64719, for example, discloses a method of obtaining a set of RGB values (point Q) to be input to a printer. The method defines one space to be output from the printer as an output color space (Lab color space that is the uniform color space) and another space to be input to the printer as an input color space (RGB color space). Further, the method is used to obtain the RGB value set (point Q) for providing a set of Lab values (point P).
Specifically, the printer prints a color patch. The color patch includes 729 colors (=9×9×9) that are uniformly distributed in the RGB color space that is an input color space of the printer. The color of the color patch is measured. A measured Lab value set (nearest point R) in the 729 colors, that is closest to the point P, is searched in the Lab color space. Next, cubic spaces are specified, each of the cubic spaces including one vertex of which is the nearest point R. Then, Lab value sets corresponding to all RGB value sets existing in the specified cubic spaces are obtained by interpolation. The nearest point R (a set of Lab values) of the point P is searched from the Lab value sets obtained by the interpolation. The RGB value set for the nearest point R (which is regarded as point Q) is stored in a color conversion table.